With development of mobile communication technologies, mobile terminal devices such as mobile phones are used more and more widely. Mobile terminal devices normally use antenna modules to convert electric power into radio waves, and vice versa, for realizing wireless transmission and reception.
A planar inverted-F antenna (PIFA) is a typical antenna module used in the mobile terminal device; the PIFA includes a planar radiating unit serving as a radiator, and a ground plate with a large area serving as a reflector. The PIFA is installed in the mobile terminal device and the ground plate is connected to a system ground of a main board of the mobile terminal device.
The PIFA is a kind of built-in antennas which is needed to receive in a plastic shell or frame of mobile terminal device. However, mobile terminal devices with metal frames are preferred by people because of their fashion appearance as well as good durability, the metal frame may bring an electromagnetic shielding effect to the antenna module of the mobile terminal device, and therefore an antenna performance of the mobile terminal device is low.
Therefore, it is desired to provide a new mobile terminal device which can overcome the aforesaid problems.